88Ra226
Radium
Alkaline earth metalsBlock sPeriod 7Group 2solid at 20 °C
- Configuration :
- [Rn] 7s²
- Atomic mass :
- 226 u
3D Bohr-model representation of the Radium atom (symbol Ra, atomic number Z=88). Electron shell configuration: 2, 8, 18, 32, 18, 8, 2 electrons.
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Bohr model · educational
Bohr model of radium
Radium (Ra) has 88 electrons, spread over 7 shells. The diagram places them on circles around the nucleus, from the K shell — the closest — outward.
| Shell | Electrons |
|---|---|
| K (n = 1) | 2 |
| L (n = 2) | 8 |
| M (n = 3) | 18 |
| N (n = 4) | 32 |
| O (n = 5) | 18 |
| P (n = 6) | 8 |
| Q (n = 7) | 2 |
The Bohr model is a teaching picture: electrons do not travel in circular orbits, but the number of electrons per shell is exact.
Electron configuration
Full1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 7s²
Short[Rn] 7s²
Valence electrons2
KLMNOPQ shells
K2
L8
M18
N32
O18
P8
Q2
Electronegativity
Pauling0.9
Allen—
Mulliken (eV)—
Atomic radii
Empirical215 pm
Calculated—
Covalent221 pm
Van der Waals283 pm
Ionic radii (Shannon-Prewitt)
+2148 pm
Successive ionisation energies
I₁509.3 kJ/mol
I₂979 kJ/mol
Electron affinity—
Oxidation states
+2
Bold states = most common.
Warm-up
Radium — do you remember?
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